1. Field of the invention
The present invention relates to wireless communication and, more particularly, to a method and apparatus for generating a transmission signal having a cycle period and spectral correlation in a multiple access system.
2. Related Art
Service requiring ultrahigh speed wireless communication, such as wireless Internet, is recently increasing rapidly. Thus, there have been carried out active researches into a communication scheme capable of guaranteeing ultrahigh speed wireless communication.
In particular, there have been carried out active researches into methods of a plurality of users efficiently using limited frequency resources, such as Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), and Code Division Multiple Access (CDMA).
Orthogonal Frequency Division Multiple Access (OFDMA) is also a method of a plurality of users being capable of efficiently using limited radio resources. In an OFDMA system, subcarriers are allocated to users and a transmission signal is generated using Fourier Transform (FT). An OFDMA system has been in the spotlight as the core technology of a Wireless Local Area Network (WLAN), such as Wi-Fi, and a cellular network, such as LTE, in that it has low complexity and it can minimize interference between users simply.
In addition, there have been researches into a signal design using a new method for supporting multiple access, such as Single Carrier-Frequency Division Multiple Access (SC-FDMA).
Meanwhile, in conventional multi-carrier systems, such as FDMA and OFDMA, subcarriers are allocated to users without being overlapped with each other. Accordingly, there is no correlation between the subcarriers and also there is no cycle period in the subcarriers. In accordance with a recent research, it has been demonstrated that frequency efficiency can be maximized by generating a signal having a specific cycle period and spectral correlation. For this, a research is carried out to generate a signal for achieving the channel capacity of a system in which a frequency band is shared and a channel including cyclostationary interference. In order to implement the research, it is essential to design a signal having the degree of freedom from a viewpoint of a cycle period and spectral correlation.